Is Distilled or Spring Water Better For Fish Tanks?

Setting up your own home aquarium?

If you’re doing this for the first time, it is imperative that you do a lot of research before bringing home your new little pet. Just like other pets, keeping fish requires a lot of work and dedication. So make sure you start it right. The first and most important thing that you must figure out is the right source of water for your fish tank.

Your aquarium will be their new home, which should ideally contain the right kind of water and environment to keep them healthy. Some fish are very fragile, and therefore, you really cannot risk their lives by opting for the wrong source of water.

So what kind of water is really the best one for a fish aquarium?

Here’s the truth:

It’s unfortunate that most people would just bring in fish as pets without really learning much about their environmental needs.

So the answer to the question above is clean water! Now, most people are also unaware of what the real definition of clean water is. To some, water that looks clean and smells fresh is good to go. The reality, however, is that most of the harmful chemical substances are colorless and cannot be detected by simply smelling the water. Ammonia is the most common substance that could kill fish, followed by chlorine and nitrate.  

Since you’re focusing on clean water here, it’s natural for ‘distilled water’ to pop in your head as an option.

But here’s another fact:

Distilled water isn’t the most ideal water for fish tanks or aquariums as it does not contain the necessary minerals your fish need in its perfect environment. And while there’s a little bit leeway on combining freshwater and distilled water for your fish tank, it isn’t really recommended. Your fish tank may contain different varieties of fish from different environments, and a combination of water sources may not be an ideal environment for them to thrive in.  

Once you’ve picked the best fish tank for your new pets, it’s now time to fill it up with the right kind of water. Keep reading to learn more about whether which type of water is better for fish tanks.

Difference Between Distilled Water & Spring Water

Bottled spring water is considered safe for drinking because it likely contains more natural minerals. Not only it makes the water healthier, but the minerals can also improve flavor. However, since it comes from different sources, if you are choosing spring water for drinking, make sure it complies with the safety standards laid down by the U.S. Environmental Protection Agency.

On the other hand, most people consider distilled water as a great option for a fish tank as it’s the purest form of water. What they don’t understand is that distilled water purification methods do not only reduce contaminants but also natural minerals. This single factor does not make it the best water for fish tanks.

Let’s dig deeper to understand the difference between distilled water and spring water.

Distilled Water

Distilled water is achieved by boiling water. Most contaminants, chemicals, and minerals steam off as the water condenses. Distillation is an effective way to remove nitrates, heavy metal, bacteria, viruses, and fungi from water. But the process also kills the minerals.

Distilled water also tends to lose its flavor because of the lack of minerals. Moreover, since it’s mostly stored in plastic bottles, it also tends to percolate plastic.

Using Distilled Water in Fish Tanks

And while the removal of harmful contaminants and microorganisms makes it great for drinking, the lack of minerals makes it flat and ineffective for a fish tank.  Minerals like calcium and iron are essential for fish to stay healthy and live longer. Moreover, since fish have semi-permeable membranes, swimming in mineral-less water can cause them a deadly experience.

A distilled water environment is traumatic for fish, especially for betta fish and the likes. In case you only have distilled water available for your fish tank, make sure to deposit all essential minerals before letting your fish free in their new environment.

Spring Water

As the name suggests, spring water comes from natural springs of water, which are often underground sources. This suggests that the spring water is usually uncontaminated. However, before it’s ready for consumption, spring water undergoes filtration process to kill bacteria and remove debris. This process does not remove important mineral content, including magnesium and calcium.

This is also why spring water has a better taste as compared to distilled water. Additionally, spring water may also contain tiny amounts of potassium and sodium.

Using Spring water In Your Aquarium

Choosing the right source of water is a crucial decision and you need to make sure that your fish take environment meets the requirement. Springwater is also an option, but it comes with a condition that you must follow to ensure that its quality is suitable for your new little swimmers. Springwater works perfectly if you’re using it to lower the hardness or the pH level of your fish tank water.

Springwater is better than distilled water, but it may not be the best option for you as it can be a little expensive to maintain. Also, different brands offer different mineral content, which may or may not be suitable for your fish. But if you’re adamant about using spring water for its quality, make sure you buy a few different brands and test them all for their pH, kH, and gH levels before picking the right one that’s perfect according to your fish preference. If cost is a major factor, consider mixing it with some tap water.

Don’t pick spring water that’s been treated with flavor, additives, or dyes.

Other Choices of Water for Your Fish Tank

It is common for people to consider other water choices for fish tanks. The following are some common options, and reasons why they are or aren’t a suitable choice for your aquarium.

Tap Water

Tap water is considered a great choice for freshwater fish provided that you install a water condition in the aquarium. Tap water is not only easily available but it is also the cheapest source of water you can use for your fish tank. If you are maintaining an aquarium of freshwater fish, tap water should work just fine.

However, the only thing you need to be very careful about is the quality of your tap water.

Let’s be real: the quality of tap water in some areas is terrible. If your tap water contains chlorine or chloramines, it can kill your fish. So before you’re ready to use tap water, neutralize it to get rid of these harmful substances. An aquarium water conditioner can help you remove it efficiently.

Lake or River Water

It’s very natural for people to think that lake or river water is best for fish since there are already fish in them. But research shows how this water can be highly contaminated and unsuitable for a fish tank. Not only there’s a risk of industrial pollution present in the water, but there’s also a likelihood for potential diseases and parasites from the wild. Definitely not recommended!


Rainwater is also often considered clean and pure and therefore, suitable for fish tanks. The truth, however, is that pollution can affect the quality of rainwater more significantly than you think. It’s again a big no-no for aquarium fish.

Bottled Water

If you aren’t satisfied with the quality of your tap water, bottled water (for drinking) is a choice. But if you don’t have a big budget, it can be a little hefty over your pocket. Also, you must really watch out for the ingredients in the bottled water. Some brands may include additives which can lead to fatal consequences for the fish.

Reverse Osmosis (RO) Water

The procedure involved in Reverse Osmosis (RO) water helps eliminate all the harmful substances in the water, making it pure H2O. You can install an RO unit or obtain it from outside. You can also find it in fish stores at a relatively lower price. But this is just 100% just pure H2O – nothing else. There are no minerals present in the water, which can be potentially risky for the fish tank.

An insignificant change in the pH levels can wreak havoc since there are no mineral deposits to buffer. In case you’re opting for RO water, make sure you get all the essential mineral deposits beforehand

Frequently Asked Question

1. Is it safe to put tap water in a fish tank?

If you take all the precautionary measures before adding the fish, tap water can be a great option. The only thing you need to be absolutely sure of is the quality of water. Also, allowing the filter to run through for several days to get rid of the chlorine makes tap water safer for a fish tank.

2. What’s the right way to prepare water for a fish tank?

Once you’ve picked up the right water source, these easy steps should help you prepare water for a fish tank:

  • Wash off any rocks, gravel, or decorations you will be adding to the aquarium. Adjust it before adding water.
  • Whatever filtration method you’re using, plug-in and filter the water to get rid of harmful substances.
  • If your water needs to be treated, do that now.
  • Leave the tank for several days until the water is ready for your fish.
  • Add fish and enjoy watching them swim around.

3. How do I clean the tank without killing my fish?

Remove the lid and clean it thoroughly before getting down to the tank. Set aside. Fill up a container with the aquarium water. This is where you will keep your fish while you are cleaning the tank. Use a net and gently transfer your fish from the tank to the container. Once the tank is clean and ready, put your fish back by simply dipping in the container. For more details, check out this video:


The information shared in this article should give you a clear idea of the right water sources for your fish tank. One important reminder: whatever you choose, just be very particular with the quality and suitability of the water according to your fish preference.

The key is to learn as much as you can beforehand so you can maintain a healthy environment for your new little fish.

Which water source is the best in your opinion? Do share with us in the comments below.


Leave a Comment